Transport Tissues Flashcards
What does xylem do?
Used to transport water and mineral ions from the roots up to the leaves
What does xylem tissue consist of?
Vessels to carry the water and dissolved mineral ions
Fibres to help support the plant
What does lignin do to make cells waterproof?
Impregnates them. Killing the cells creating a column of dead cells. The xylem.
How does lignin help?
Strengthens vessel walls
Prevents vessel from collapsing
Keeps vessel open when water in short supply
Some spaces lignification is not complete inn the vessel what does this allow?
Water to flow from one vessel to another
What are the holes connecting two vessels called?
Bordered pits
Why are xylem tubes narrow?
So that they don’t break easily and capillary actin can be effective
Why is the flow of water not impeded?
There are no cross-walls
There are no cell contents, nucleus or cytoplasm
Lignin thickening prevents the walls from collapsing
What does phloem transport?
Mainly sucrose and amino acids
What are sieve tube elements?
They make up the tubes in phloem tissue that carry sap
What do sieve plates do?
Allow movement of sap from one element to another
What do companion cells do?
Carry out the metabolic processes needed to load assimilates actively into the sieve tubes
What are companion cells?
The cells that help to load sucrose into the sieve tubes
What are sieve tube elements?
Elements which make up the tubes in the phloem tissue that can carry sap up and down the plant.
What are xylem vessels?
The tubes which carry water up the plant.
